RegisterCACertificate

Registers a CA certificate with AWS IoT. This CA certificate can then be used to sign
device
certificates, which can be then registered with AWS IoT. You can register up to 10
CA certificates per AWS
account that have the same subject field. This enables you to have up to 10 certificate
authorities sign your
device certificates. If you have more than one CA certificate registered, make sure
you pass the CA certificate
when you register your device certificates with the RegisterCertificate API.